req-1.0.0: Easy-to-use, type-safe, expandable, high-level HTTP library

Copyright © 2016–2017 Mark Karpov BSD 3 clause Mark Karpov experimental portable None Haskell2010

Network.HTTP.Req

Description

The documentation below is structured in such a way that the most important information is presented first: you learn how to do HTTP requests, how to embed them in any monad you have, and then it gives you details about less-common things you may want to know about. The documentation is written with sufficient coverage of details and examples, and it's designed to be a complete tutorial on its own.

(A modest intro goes here, click on req to start making requests.)

Req is an easy-to-use, type-safe, expandable, high-level HTTP library that just works without any fooling around.

What does the phrase “easy-to-use” mean? It means that the library is designed to be beginner-friendly so it's simple to add to your monad stack, intuitive to work with, well-documented, and does not get in your way. Doing HTTP requests is a common task and a Haskell library for this should be very approachable and clear to beginners, thus certain compromises were made. For example, one cannot currently modify ManagerSettings of the default manager because the library always uses the same implicit global manager for simplicity and maximal connection sharing. There is a way to use your own manager with different settings, but it requires a bit more typing.

“Type-safe” means that the library is protective and eliminates certain classes of errors. For example, we have correct-by-construction Urls, it's guaranteed that the user does not send the request body when using methods like GET or OPTIONS, and the amount of implicit assumptions is minimized by making the user specify his/her intentions in an explicit form (for example, it's not possible to avoid specifying the body or method of a request). Authentication methods that assume HTTPS force the user to use HTTPS at the type level. The library also carefully hides underlying types from the lower-level http-client package because those types are not safe enough (for example Request is an instance of IsString and, if it's malformed, it will blow up at run-time).

“Expandable” refers to the ability of the library to be expanded without having to resort to ugly hacking. For example, it's possible to define your own HTTP methods, create new ways to construct the body of a request, create new authorization options, perform a request in a different way, and create your own methods to parse and represent a response. As a user extends the library to satisfy his/her special needs, the new solutions will work just like the built-ins. However, all of the common cases are also covered by the library out-of-the-box.

“High-level” means that there are less details to worry about. The library is a result of my experiences as a Haskell consultant. Working for several clients, who had very different projects, showed me that the library should adapt easily to any particular style of writing Haskell applications. For example, some people prefer throwing exceptions, while others are concerned with purity. Just define handleHttpException accordingly when making your monad instance of MonadHttp and it will play together seamlessly. Finally, the library cuts boilerplate down considerably, and helps you write concise, easy to read, and maintainable code.

Using with other libraries

• You won't need the low-level interface of http-client most of the time, but when you do, it's better to do a qualified import, because http-client has naming conflicts with req.
• For streaming of large request bodies see the companion package req-conduit: https://hackage.haskell.org/package/req-conduit.

Lightweight, no risk solution

The library uses the following mature packages under the hood to guarantee you the best experience:

It's important to note that since we leverage well-known libraries that the whole Haskell ecosystem uses, there is no risk in using req. The machinery for performing requests is the same as with http-conduit and wreq. The only difference is the API.

Synopsis

Making a request

To make an HTTP request you normally need only one function: req.

Arguments

 :: (MonadHttp m, HttpMethod method, HttpBody body, HttpResponse response, HttpBodyAllowed (AllowsBody method) (ProvidesBody body)) => method HTTP method -> Url scheme Url—location of resource -> body Body of the request -> Proxy response A hint how to interpret response -> Option scheme Collection of optional parameters -> m response Response

Make an HTTP request. The function takes 5 arguments, 4 of which specify required parameters and the final Option argument is a collection of optional parameters.

Let's go through all the arguments first: req method url body response options.

method is an HTTP method such as GET or POST. The documentation has a dedicated section about HTTP methods below.

url is a Url that describes location of resource you want to interact with.

body is a body option such as NoReqBody or ReqBodyJson. The tutorial has a section about HTTP bodies, but usage is very straightforward and should be clear from the examples below.

response is a type hint how to make and interpret response of an HTTP request. Out-of-the-box it can be the following:

Finally, options is a Monoid that holds a composite Option for all other optional settings like query parameters, headers, non-standard port number, etc. There are quite a few things you can put there, see the corresponding section in the documentation. If you don't need anything at all, pass mempty.

Note that if you use req to do all your requests, connection sharing and reuse is done for you automatically.

See the examples below to get on the speed quickly.

Examples

First, this is a piece of boilerplate that should be in place before you try the examples:

{-# LANGUAGE OverloadedStrings #-}

module Main (main) where

import Control.Exception (throwIO)
import Data.Aeson
import Data.Maybe (fromJust)
import Data.Monoid ((<>))
import Data.Text (Text)
import GHC.Generics
import Network.HTTP.Req
import qualified Data.ByteString.Char8 as B

instance MonadHttp IO where
handleHttpException = throwIO

We will be making requests against the https://httpbin.org service.

Make a GET request, grab 5 random bytes:

main :: IO ()
main = do
let n :: Int
n = 5
bs <- req GET (https "httpbin.org" /: "bytes" /~ n) NoReqBody bsResponse mempty
B.putStrLn (responseBody bs)

The same, but now we use a query parameter named "seed" to control seed of the generator:

main :: IO ()
main = do
let n, seed :: Int
n    = 5
seed = 100
bs <- req GET (https "httpbin.org" /: "bytes" /~ n) NoReqBody bsResponse $"seed" =: seed B.putStrLn (responseBody bs) POST JSON data and get some info about the POST request: data MyData = MyData { size :: Int , color :: Text } deriving (Show, Generic) instance ToJSON MyData instance FromJSON MyData main :: IO () main = do let myData = MyData { size = 6 , color = "Green" } v <- req POST (https "httpbin.org" /: "post") (ReqBodyJson myData) jsonResponse mempty print (responseBody v :: Value) Sending URL-encoded body: main :: IO () main = do let params = "foo" =: ("bar" :: Text) <> queryFlag "baz" response <- req POST (https "httpbin.org" /: "post") (ReqBodyUrlEnc params) jsonResponse mempty print (responseBody response :: Value) Using various optional parameters and URL that is not known in advance: main :: IO () main = do -- This is an example of what to do when URL is given dynamically. Of -- course in a real application you may not want to use 'fromJust'. let (url, options) = fromJust (parseUrlHttps "https://httpbin.org/get?foo=bar") response <- req GET url NoReqBody jsonResponse$
"from" =: (15 :: Int)           <>
"to"   =: (67 :: Int)           <>
options                         <> -- contains the ?foo=bar part
port 443 -- here you can put any port of course
print (responseBody response :: Value)

Arguments

 :: (MonadHttp m, HttpMethod method, HttpBody body, HttpBodyAllowed (AllowsBody method) (ProvidesBody body)) => method HTTP method -> Url scheme Url—location of resource -> body Body of the request -> Option scheme Collection of optional parameters -> (Response BodyReader -> IO a) How to consume response -> m a Result

A version of req that does not use one of the predefined instances of HttpResponse but instead allows the user to consume Response BodyReader manually, in a custom way.

Since: 1.0.0

Arguments

 :: (MonadHttp m, HttpMethod method, HttpBody body, HttpBodyAllowed (AllowsBody method) (ProvidesBody body)) => method HTTP method -> Url scheme Url—location of resource -> body Body of the request -> Option scheme Collection of optional parameters -> (Request -> Manager -> m a) How to perform request -> m a Result

Mostly like req with respect to its arguments, but accepts a callback that allows to perform a request in arbitrary fashion.

This function does not perform handling/wrapping exceptions, checking response (with httpConfigCheckResponse), and retrying. It only prepares Request and allows you to use it.

Since: 0.3.0

withReqManager :: MonadIO m => (Manager -> m a) -> m a Source #

Perform an action using the global implicit Manager that the rest of the library uses. This allows to reuse connections that the Manager controls.

To use req in your monad, all you need to do is to make the monad an instance of the MonadHttp type class.

When writing a library, keep your API polymorphic in terms of MonadHttp, only define instance of MonadHttp in final application. Another option is to use newtype wrapped monad stack and define MonadHttp for it. As of version 0.4.0, the Req monad that follows this strategy is provided out-of-the-box (see below).

class MonadIO m => MonadHttp m where Source #

A type class for monads that support performing HTTP requests. Typically, you only need to define the handleHttpException method unless you want to tweak HttpConfig.

Minimal complete definition

handleHttpException

Methods

This method describes how to deal with HttpException that was caught by the library. One option is to re-throw it if you are OK with exceptions, but if you prefer working with something like MonadError, this is the right place to pass it to throwError.

Return HttpConfig to be used when performing HTTP requests. Default implementation returns its def value, which is described in the documentation for the type. Common usage pattern with manually defined getHttpConfig is to return some hard-coded value, or a value extracted from MonadReader if a more flexible approach to configuration is desirable.

Instances

 Source # Methods

HttpConfig contains general and default settings to be used when making HTTP requests.

Constructors

 HttpConfig FieldshttpConfigProxy :: Maybe ProxyProxy to use. By default values of HTTP_PROXY and HTTPS_PROXY environment variables are respected, this setting overwrites them. Default value: Nothing.httpConfigRedirectCount :: IntHow many redirects to follow when getting a resource. Default value: 10.httpConfigAltManager :: Maybe ManagerAlternative Manager to use. Nothing (default value) means that the default implicit manager will be used (that's what you want in 99% of cases).httpConfigCheckResponse :: forall b. Request -> Response b -> ByteString -> Maybe HttpExceptionContentFunction to check the response immediately after receiving the status and headers, before streaming of response body. The third argument is the beginning of response body (typically first 1024 bytes). This is used for throwing exceptions on non-success status codes by default (set to \_ _ _ -> Nothing if this behavior is not desirable).When the value this function returns is Nothing, nothing will happen. When it there is HttpExceptionContent inside Just, it will be thrown.Throwing is better then just returning a request with non-2xx status code because in that case something is wrong and we need a way to short-cut execution (also remember that Req retries automatically on request timeouts and such, so when your request fails, it's certainly something exceptional). The thrown exception is caught by the library though and is available in handleHttpException.Note: signature of this function was changed in the version 1.0.0.Since: 0.3.0httpConfigRetryPolicy :: RetryPolicyThe retry policy to use for request retrying. By default def is used (see RetryPolicyM).Note: signature of this function was changed in the version 1.0.0.Since: 0.3.0httpConfigRetryJudge :: forall b. RetryStatus -> Response b -> BoolThe function is used to decide whether to retry a request. True means that the request should be retried.Note: signature of this function was changed in the version 1.0.0.Since: 0.3.0

Instances

 Source # Methods

data Req a Source #

A monad that allows to run req in any IO-enabled monad without having to define new instances.

Since: 0.4.0

Instances

 Source # Methods(>>=) :: Req a -> (a -> Req b) -> Req b #(>>) :: Req a -> Req b -> Req b #return :: a -> Req a #fail :: String -> Req a # Source # Methodsfmap :: (a -> b) -> Req a -> Req b #(<$) :: a -> Req b -> Req a # Source # Methodspure :: a -> Req a #(<*>) :: Req (a -> b) -> Req a -> Req b #(*>) :: Req a -> Req b -> Req b #(<*) :: Req a -> Req b -> Req a # Source # MethodsliftIO :: IO a -> Req a # Source # Methods Source # MethodsliftBase :: IO α -> Req α # Source # Associated Typestype StM (Req :: * -> *) a :: * # MethodsliftBaseWith :: (RunInBase Req IO -> IO a) -> Req a #restoreM :: StM Req a -> Req a # type StM Req a Source # type StM Req a = a Arguments  :: MonadIO m => HttpConfig HttpConfig to use -> Req a Computation to run -> m a Run a computation in the Req monad with the given HttpConfig. In case of exceptional situation an HttpException will be thrown. Since: 0.4.0 Request Method The package supports all methods as defined by RFC 2616, and PATCH which is defined by RFC 5789—that should be enough to talk to RESTful APIs. In some cases, however, you may want to add more methods (e.g. you work with WebDAV https://en.wikipedia.org/wiki/WebDAV); no need to compromise on type safety and hack, it only takes a couple of seconds to define a new method that will works seamlessly, see HttpMethod. data GET Source # GET method. Constructors  GET Instances  Source # Associated Types Methods type AllowsBody GET Source # type AllowsBody GET = NoBody data POST Source # POST method. Constructors  POST Instances  Source # Associated Types Methods type AllowsBody POST Source # data HEAD Source # HEAD method. Constructors  HEAD Instances  Source # Associated Types Methods type AllowsBody HEAD Source # type AllowsBody HEAD = NoBody data PUT Source # PUT method. Constructors  PUT Instances  Source # Associated Types Methods type AllowsBody PUT Source # data DELETE Source # DELETE method. This data type does not allow having request body with DELETE requests, as it should be. However some APIs may expect DELETE requests to have bodies, in that case define your own variation of DELETE method and allow it to have a body. Constructors  DELETE Instances  Source # Associated Types Methods type AllowsBody DELETE Source # data TRACE Source # TRACE method. Constructors  TRACE Instances  Source # Associated Types Methods type AllowsBody TRACE Source # data CONNECT Source # CONNECT method. Constructors  CONNECT Instances  Source # Associated Types Methods Source # data OPTIONS Source # OPTIONS method. Constructors  OPTIONS Instances  Source # Associated Types Methods Source # data PATCH Source # PATCH method. Constructors  PATCH Instances  Source # Associated Types Methods type AllowsBody PATCH Source # class HttpMethod a where Source # A type class for types that can be used as an HTTP method. To define a non-standard method, follow this example that defines COPY: data COPY = COPY instance HttpMethod COPY where type AllowsBody COPY = 'CanHaveBody httpMethodName Proxy = "COPY" Minimal complete definition httpMethodName Associated Types type AllowsBody a :: CanHaveBody Source # Type function AllowsBody returns a type of kind CanHaveBody which tells the rest of the library whether the method can have a body or not. We use the special type CanHaveBody lifted to the kind level instead of Bool to get more user-friendly compiler messages. Methods Return name of the method as a ByteString. Instances  Source # Associated Types Methods Source # Associated Types Methods Source # Associated Types Methods Source # Associated Types Methods Source # Associated Types Methods Source # Associated Types Methods Source # Associated Types Methods Source # Associated Types Methods Source # Associated Types Methods URL We use Urls which are correct by construction, see Url. To build a Url from a ByteString, use parseUrlHttp or parseUrlHttps. data Url scheme Source # Request's Url. Start constructing your Url with http or https specifying the scheme and host at the same time. Then use the (/~) and (/:) operators to grow the path one piece at a time. Every single piece of path will be url(percent)-encoded, so using (/~) and (/:) is the only way to have forward slashes between path segments. This approach makes working with dynamic path segments easy and safe. See examples below how to represent various Urls (make sure the OverloadedStrings language extension is enabled). Examples http "httpbin.org" -- http://httpbin.org https "httpbin.org" -- https://httpbin.org https "httpbin.org" /: "encoding" /: "utf8" -- https://httpbin.org/encoding/utf8 https "httpbin.org" /: "foo" /: "bar/baz" -- https://httpbin.org/foo/bar%2Fbaz https "httpbin.org" /: "bytes" /~ (10 :: Int) -- https://httpbin.org/bytes/10 https "юникод.рф" -- https://%D1%8E%D0%BD%D0%B8%D0%BA%D0%BE%D0%B4.%D1%80%D1%84 Instances  Eq (Url scheme) Source # Methods(==) :: Url scheme -> Url scheme -> Bool #(/=) :: Url scheme -> Url scheme -> Bool # Typeable Scheme scheme => Data (Url scheme) Source # Methodsgfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Url scheme -> c (Url scheme) #gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Url scheme) #toConstr :: Url scheme -> Constr #dataTypeOf :: Url scheme -> DataType #dataCast1 :: Typeable (* -> *) t => (forall d. Data d => c (t d)) -> Maybe (c (Url scheme)) #dataCast2 :: Typeable (* -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Url scheme)) #gmapT :: (forall b. Data b => b -> b) -> Url scheme -> Url scheme #gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Url scheme -> r #gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Url scheme -> r #gmapQ :: (forall d. Data d => d -> u) -> Url scheme -> [u] #gmapQi :: Int -> (forall d. Data d => d -> u) -> Url scheme -> u #gmapM :: Monad m => (forall d. Data d => d -> m d) -> Url scheme -> m (Url scheme) #gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Url scheme -> m (Url scheme) #gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Url scheme -> m (Url scheme) # Ord (Url scheme) Source # Methodscompare :: Url scheme -> Url scheme -> Ordering #(<) :: Url scheme -> Url scheme -> Bool #(<=) :: Url scheme -> Url scheme -> Bool #(>) :: Url scheme -> Url scheme -> Bool #(>=) :: Url scheme -> Url scheme -> Bool #max :: Url scheme -> Url scheme -> Url scheme #min :: Url scheme -> Url scheme -> Url scheme # Show (Url scheme) Source # MethodsshowsPrec :: Int -> Url scheme -> ShowS #show :: Url scheme -> String #showList :: [Url scheme] -> ShowS # Generic (Url scheme) Source # Associated Typestype Rep (Url scheme) :: * -> * # Methodsfrom :: Url scheme -> Rep (Url scheme) x #to :: Rep (Url scheme) x -> Url scheme # type Rep (Url scheme) Source # type Rep (Url scheme) = D1 (MetaData "Url" "Network.HTTP.Req" "req-1.0.0-3YwpXfp11CqEYC5hgP7owv" False) (C1 (MetaCons "Url" PrefixI False) ((:*:) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Scheme)) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (NonEmpty Text))))) Given host name, produce a Url which have “http” as its scheme and empty path. This also sets port to 80. Given host name, produce a Url which have “https” as its scheme and empty path. This also sets port to 443. (/~) :: ToHttpApiData a => Url scheme -> a -> Url scheme infixl 5 Source # Grow given Url appending a single path segment to it. Note that the path segment can be of any type that is an instance of ToHttpApiData. (/:) :: Url scheme -> Text -> Url scheme infixl 5 Source # Type-constrained version of (/~) to remove ambiguity in the cases when next URL piece is a Text literal. parseUrlHttp :: ByteString -> Maybe (Url Http, Option scheme) Source # The parseUrlHttp function provides an alternative method to get Url (possibly with some Options) from a ByteString. This is useful when you are given a URL to query dynamically and don't know it beforehand. The function parses ByteString because it's the correct type to represent a URL, as Url cannot contain characters outside of ASCII range, thus we can consider every character a Word8 value. This function only parses Url (scheme, host, path) and optional query parameters that are returned as Option. It does not parse method name or authentication info from given ByteString. parseUrlHttps :: ByteString -> Maybe (Url Https, Option scheme) Source # Just like parseUrlHttp, but expects “https” scheme. Body A number of options for request bodies are available. The Content-Type header is set for you automatically according to the body option you use (it's always specified in documentation for a given body option). To add your own way to represent request body, define an instance of HttpBody. data NoReqBody Source # This data type represents empty body of an HTTP request. This is the data type to use with HttpMethods that cannot have a body, as it's the only type for which ProvidesBody returns NoBody. Using of this body option does not set the Content-Type header. Constructors  NoReqBody Instances  Source # Methods newtype ReqBodyJson a Source # This body option allows to use a JSON object as request body—probably the most popular format right now. Just wrap a data type that is an instance of ToJSON type class and you are done: it will be converted to JSON and inserted as request body. This body option sets the Content-Type header to "application/json; charset=utf-8" value. Constructors  ReqBodyJson a Instances  ToJSON a => HttpBody (ReqBodyJson a) Source # Methods newtype ReqBodyFile Source # This body option streams request body from a file. It is expected that the file size does not change during the streaming. Using of this body option does not set the Content-Type header. Constructors  ReqBodyFile FilePath Instances  Source # Methods newtype ReqBodyBs Source # HTTP request body represented by a strict ByteString. Using of this body option does not set the Content-Type header. Constructors  ReqBodyBs ByteString Instances  Source # Methods newtype ReqBodyLbs Source # HTTP request body represented by a lazy ByteString. Using of this body option does not set the Content-Type header. Constructors  ReqBodyLbs ByteString Instances  Source # Methods newtype ReqBodyUrlEnc Source # Form URL-encoded body. This can hold a collection of parameters which are encoded similarly to query parameters at the end of query string, with the only difference that they are stored in request body. The similarity is reflected in the API as well, as you can use the same combinators you would use to add query parameters: (=:) and queryFlag. This body option sets the Content-Type header to "application/x-www-form-urlencoded" value. Constructors  ReqBodyUrlEnc FormUrlEncodedParam Instances  Source # Methods An opaque monoidal value that allows to collect URL-encoded parameters to be wrapped in ReqBodyUrlEnc. Instances  Source # Methods Source # Methods Source # Methods Multipart form data. Please consult the Network.HTTP.Client.MultipartFormData module for how to construct parts, then use reqBodyMultipart to create actual request body from the parts. reqBodyMultipart is the only way to get a value of the type ReqBodyMultipart, as its constructor is not exported on purpose. Example import Control.Exception (throwIO) import qualified Network.HTTP.Client.MultipartFormData as LM import Network.HTTP.Req instance MonadHttp IO where handleHttpException = throwIO main :: IO () main = do body <- reqBodyMultipart [ LM.partBS "title" "My Image" , LM.partFileSource "file1" "/tmp/image.jpg" ] response <- req POST (http "example.com" /: "post") body bsResponse mempty print$ responseBody response

Since: 0.2.0

Instances

 Source # Methods

reqBodyMultipart :: MonadIO m => [Part] -> m ReqBodyMultipart Source #

Create ReqBodyMultipart request body from a collection of Parts.

Since: 0.2.0

class HttpBody body where Source #

A type class for things that can be interpreted as an HTTP RequestBody.

Minimal complete definition

getRequestBody

Methods

getRequestBody :: body -> RequestBody Source #

How to get actual RequestBody.

This method allows to optionally specify value of Content-Type header that should be used with particular body option. By default it returns Nothing and so Content-Type is not set.

Instances

 Source # Methods Source # Methods Source # Methods Source # Methods Source # Methods Source # Methods ToJSON a => HttpBody (ReqBodyJson a) Source # Methods

type family ProvidesBody body :: CanHaveBody where ... Source #

The type function recognizes NoReqBody as having NoBody, while any other body option CanHaveBody. This forces user to use NoReqBody with GET method and other methods that should not send a body.

Equations

 ProvidesBody NoReqBody = NoBody ProvidesBody body = CanHaveBody

type family HttpBodyAllowed (allowsBody :: CanHaveBody) (providesBody :: CanHaveBody) :: Constraint where ... Source #

This type function allows any HTTP body if method says it CanHaveBody. When the method says it should have NoBody, the only body option to use is NoReqBody.

Note: users of GHC 8.0.1 and later will see a slightly more friendly error message when method does not allow a body and body is provided.

Equations

 HttpBodyAllowed NoBody NoBody = () HttpBodyAllowed CanHaveBody body = () HttpBodyAllowed NoBody CanHaveBody = TypeError (Text "This HTTP method does not allow attaching a request body.")

Optional parameters

Optional parameters to a request include things like query parameters, headers, port number, etc. All optional parameters have the type Option, which is a Monoid. This means that you can use mempty as the last argument of req to specify no optional parameters, or combine Options using mappend or (<>) to have several of them at once.

data Option scheme Source #

The opaque Option type is a Monoid you can use to pack collection of optional parameters like query parameters and headers. See sections below to learn which Option primitives are available.

Instances

 Semigroup (Option scheme) Source # Methods(<>) :: Option scheme -> Option scheme -> Option scheme #sconcat :: NonEmpty (Option scheme) -> Option scheme #stimes :: Integral b => b -> Option scheme -> Option scheme # Monoid (Option scheme) Source # Methodsmempty :: Option scheme #mappend :: Option scheme -> Option scheme -> Option scheme #mconcat :: [Option scheme] -> Option scheme # QueryParam (Option scheme) Source # MethodsqueryParam :: ToHttpApiData a => Text -> Maybe a -> Option scheme Source #

Query parameters

This section describes a polymorphic interface that can be used to construct query parameters (of the type Option) and form URL-encoded bodies (of the type FormUrlEncodedParam).

(=:) :: (QueryParam param, ToHttpApiData a) => Text -> a -> param infix 7 Source #

This operator builds a query parameter that will be included in URL of your request after the question sign ?. This is the same syntax you use with form URL encoded request bodies.

This operator is defined in terms of queryParam:

name =: value = queryParam name (pure value)

queryFlag :: QueryParam param => Text -> param Source #

Construct a flag, that is, valueless query parameter. For example, in the following URL "a" is a flag, while "b" is a query parameter with a value:

https://httpbin.org/foo/bar?a&b=10

This operator is defined in terms of queryParam:

queryFlag name = queryParam name (Nothing :: Maybe ())

class QueryParam param where Source #

A type class for query-parameter-like things. The reason to have an overloaded queryParam is to be able to use it as an Option and as a FormUrlEncodedParam when constructing form URL encoded request bodies. Having the same syntax for these cases seems natural and user-friendly.

Minimal complete definition

queryParam

Methods

queryParam :: ToHttpApiData a => Text -> Maybe a -> param Source #

Create a query parameter with given name and value. If value is Nothing, it won't be included at all (i.e. you create a flag this way). It's recommended to use (=:) and queryFlag instead of this method, because they are easier to read.

Instances

 Source # Methods QueryParam (Option scheme) Source # MethodsqueryParam :: ToHttpApiData a => Text -> Maybe a -> Option scheme Source #

Arguments

 :: ByteString Header name -> ByteString Header value -> Option scheme

Create an Option that adds a header. Note that if you mappend two headers with the same names the leftmost header will win. This means, in particular, that you cannot create a request with several headers of the same name.

Support for cookies is quite minimalistic at the moment. It's possible to specify which cookies to send using cookieJar and inspect Response to extract CookieJar from it (see responseCookieJar).

cookieJar :: CookieJar -> Option scheme Source #

Use the given CookieJar. A CookieJar can be obtained from a Response record.

Authentication

This section provides the common authentication helpers in the form of Options. You should always prefer the provided authentication Options to manual construction of headers because it ensures that you only use one authentication method at a time (they overwrite each other) and provides additional type safety that prevents leaking of credentials in the cases when authentication relies on HTTPS for encrypting sensitive data.

Arguments

 :: ByteString Username -> ByteString Password -> Option Https Auth Option

The Option adds basic authentication.

Arguments

 :: ByteString Username -> ByteString Password -> Option scheme Auth Option

An alternative to basicAuth which works for any scheme. Note that using basic access authentication without SSL/TLS is vulnerable to attacks. Use basicAuth instead unless you know what you are doing.

Since: 0.3.1

Arguments

 :: ByteString Consumer token -> ByteString Consumer secret -> ByteString OAuth token -> ByteString OAuth token secret -> Option scheme Auth Option

The Option adds OAuth1 authentication.

Since: 0.2.0

Arguments

 :: ByteString Token -> Option Https Auth Option

The Option adds an OAuth2 bearer token. This is treated by many services as the equivalent of a username and password.

The Option is defined as:

oAuth2Bearer token = header "Authorization" ("Bearer " <> token)

Arguments

 :: ByteString Token -> Option Https Auth Option

The Option adds a not-quite-standard OAuth2 bearer token (that seems to be used only by GitHub). This will be treated by whatever services accept it as the equivalent of a username and password.

The Option is defined as:

oAuth2Token token = header "Authorization" ("token" <> token)

Other

port :: Int -> Option scheme Source #

Specify the port to connect to explicitly. Normally, Url you use determines the default port: 80 for HTTP and 443 for HTTPS. This Option allows to choose an arbitrary port overwriting the defaults.

Arguments

 :: (ByteString -> Bool) Predicate that is given MIME type, it returns True when content should be decompressed on the fly. -> Option scheme

This Option controls whether gzipped data should be decompressed on the fly. By default everything except for "application/x-tar" is decompressed, i.e. we have:

decompress (/= "application/x-tar")

You can also choose to decompress everything like this:

decompress (const True)

Arguments

 :: Int Number of microseconds to wait -> Option scheme

Specify the number of microseconds to wait for response. The default value is 30 seconds (defined in ManagerSettings of connection Manager).

Arguments

 :: Int Major version number -> Int Minor version number -> Option scheme

HTTP version to send to the server, the default is HTTP 1.1.

Response

Response interpretations

Make a request and ignore the body of the response.

Instances

 Source # Associated Types Methods Source # type HttpResponseBody IgnoreResponse = ()

Use this as the fourth argument of req to specify that you want it to ignore the response body.

data JsonResponse a Source #

Make a request and interpret the body of the response as JSON. The handleHttpException method of MonadHttp instance corresponding to monad in which you use req will determine what to do in the case when parsing fails (the JsonHttpException constructor will be used).

Instances

 Source # Associated Typestype HttpResponseBody (JsonResponse a) :: * Source # Methods type HttpResponseBody (JsonResponse a) Source # type HttpResponseBody (JsonResponse a) = a

Use this as the fourth argument of req to specify that you want it to return the JsonResponse interpretation.

Make a request and interpret the body of the response as a strict ByteString.

Instances

 Source # Associated Types Methods Source #

Use this as the fourth argument of req to specify that you want to interpret the response body as a strict ByteString.

Make a request and interpret the body of the response as a lazy ByteString.

Instances

 Source # Associated Types Methods Source #

Use this as the fourth argument of req to specify that you want to interpret the response body as a lazy ByteString.

Inspecting a response

responseBody :: HttpResponse response => response -> HttpResponseBody response Source #

Get the response body.

responseStatusCode :: HttpResponse response => response -> Int Source #

Get the response status code.

responseStatusMessage :: HttpResponse response => response -> ByteString Source #

Get the response status message.

Arguments

 :: HttpResponse response => response Response interpretation -> ByteString Header to lookup -> Maybe ByteString Header value if found

Lookup a particular header from a response.

responseCookieJar :: HttpResponse response => response -> CookieJar Source #

Get the response CookieJar.

Defining your own interpretation

To create a new response interpretation you just need to make your data type an instance of the HttpResponse type class.

class HttpResponse response where Source #

A type class for response interpretations. It allows to describe how to consume response from a Response BodyReader and produce the final result that is to be returned to the user.

Minimal complete definition

Associated Types

type HttpResponseBody response :: * Source #

The associated type is the type of body that can be extracted from an instance of HttpResponse.

Methods

toVanillaResponse :: response -> Response (HttpResponseBody response) Source #

The method describes how to get the underlying Response record.

getHttpResponse :: Response BodyReader -> IO response Source #

This method describes how to consume response body and, more generally, obtain response value from Response BodyReader.

Note: BodyReader is nothing but IO ByteString. You should call this action repeatedly until it yields the empty ByteString. In that case streaming of response is finished (which apparently leads to closing of the connection, so don't call the reader after it has returned the empty ByteString once) and you can concatenate the chunks to obtain the final result. (Of course you could as well stream the contents to a file or do whatever you want.)

Note: signature of this function was changed in the version 1.0.0.

Instances

 Source # Associated Types Methods Source # Associated Types Methods Source # Associated Types Methods Source # Associated Typestype HttpResponseBody (JsonResponse a) :: * Source # Methods

Other

Exceptions that this library throws.

Constructors

 VanillaHttpException HttpException A wrapper with an HttpException from Network.HTTP.Client JsonHttpException String A wrapper with Aeson-produced String describing why decoding failed

Instances

 Source # MethodsshowList :: [HttpException] -> ShowS # Source # Associated Typestype Rep HttpException :: * -> * # Methods Source # Methods type Rep HttpException Source # type Rep HttpException = D1 (MetaData "HttpException" "Network.HTTP.Req" "req-1.0.0-3YwpXfp11CqEYC5hgP7owv" False) ((:+:) (C1 (MetaCons "VanillaHttpException" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 HttpException))) (C1 (MetaCons "JsonHttpException" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 String))))

A simple type isomorphic to Bool that we only have for better error messages. We use it as a kind and its data constructors as type-level tags.

Constructors

 CanHaveBody Indeed can have a body NoBody Should not have a body

data Scheme Source #

A type-level tag that specifies URL scheme used (and thus if HTTPS is enabled). This is used to force TLS requirement for some authentication Options.

Constructors

 Http HTTP Https HTTPS

Instances

 Source # Methods(==) :: Scheme -> Scheme -> Bool #(/=) :: Scheme -> Scheme -> Bool # Source # Methodsgfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Scheme -> c Scheme #gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Scheme #dataCast1 :: Typeable (* -> *) t => (forall d. Data d => c (t d)) -> Maybe (c Scheme) #dataCast2 :: Typeable (* -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Scheme) #gmapT :: (forall b. Data b => b -> b) -> Scheme -> Scheme #gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Scheme -> r #gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Scheme -> r #gmapQ :: (forall d. Data d => d -> u) -> Scheme -> [u] #gmapQi :: Int -> (forall d. Data d => d -> u) -> Scheme -> u #gmapM :: Monad m => (forall d. Data d => d -> m d) -> Scheme -> m Scheme #gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Scheme -> m Scheme #gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Scheme -> m Scheme # Source # Methods(<) :: Scheme -> Scheme -> Bool #(<=) :: Scheme -> Scheme -> Bool #(>) :: Scheme -> Scheme -> Bool #(>=) :: Scheme -> Scheme -> Bool #max :: Scheme -> Scheme -> Scheme #min :: Scheme -> Scheme -> Scheme # Source # MethodsshowsPrec :: Int -> Scheme -> ShowS #showList :: [Scheme] -> ShowS # Source # Associated Typestype Rep Scheme :: * -> * # Methodsfrom :: Scheme -> Rep Scheme x #to :: Rep Scheme x -> Scheme # type Rep Scheme Source # type Rep Scheme = D1 (MetaData "Scheme" "Network.HTTP.Req" "req-1.0.0-3YwpXfp11CqEYC5hgP7owv" False) ((:+:) (C1 (MetaCons "Http" PrefixI False) U1) (C1 (MetaCons "Https" PrefixI False) U1))